1 /* Copyright (C) 1991-2017 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
20 #include <libc-lock.h>
28 #include <timezone/tzfile.h>
30 #define SECSPERDAY 86400
32 char *__tzname
[2] = { (char *) "GMT", (char *) "GMT" };
34 long int __timezone
= 0L;
36 weak_alias (__tzname
, tzname
)
37 weak_alias (__daylight
, daylight
)
38 weak_alias (__timezone
, timezone
)
40 /* This locks all the state variables in tzfile.c and this file. */
41 __libc_lock_define_initialized (static, tzset_lock
)
43 /* This structure contains all the information about a
44 timezone given in the POSIX standard TZ envariable. */
50 enum { J0
, J1
, M
} type
; /* Interpretation of: */
51 unsigned short int m
, n
, d
; /* Month, week, day. */
52 int secs
; /* Time of day. */
54 long int offset
; /* Seconds east of GMT (west if < 0). */
56 /* We cache the computed time of change for a
57 given year so we don't have to recompute it. */
58 time_t change
; /* When to change to this zone. */
59 int computed_for
; /* Year above is computed for. */
62 /* tz_rules[0] is standard, tz_rules[1] is daylight. */
63 static tz_rule tz_rules
[2];
66 static void compute_change (tz_rule
*rule
, int year
) __THROW internal_function
;
67 static void tzset_internal (int always
);
69 /* List of buffers containing time zone strings. */
72 struct tzstring_l
*next
;
73 size_t len
; /* strlen(data) - doesn't count terminating NUL! */
77 static struct tzstring_l
*tzstring_list
;
79 /* Allocate a permanent home for the first LEN characters of S. It
80 will never be moved or deallocated, but may share space with other
81 strings. Don't modify the returned string. */
83 __tzstring_len (const char *s
, size_t len
)
86 struct tzstring_l
*t
, *u
, *new;
88 /* Walk the list and look for a match. If this string is the same
89 as the end of an already-allocated string, it can share space. */
90 for (u
= t
= tzstring_list
; t
; u
= t
, t
= t
->next
)
93 p
= &t
->data
[t
->len
- len
];
94 if (memcmp (s
, p
, len
) == 0)
98 /* Not found; allocate a new buffer. */
99 new = malloc (sizeof (struct tzstring_l
) + len
+ 1);
105 memcpy (new->data
, s
, len
);
106 new->data
[len
] = '\0';
116 /* Allocate a permanent home for S. It will never be moved or
117 deallocated, but may share space with other strings. Don't modify
118 the returned string. */
120 __tzstring (const char *s
)
122 return __tzstring_len (s
, strlen (s
));
131 __daylight
= tz_rules
[0].offset
!= tz_rules
[1].offset
;
132 __timezone
= -tz_rules
[0].offset
;
133 __tzname
[0] = (char *) tz_rules
[0].name
;
134 __tzname
[1] = (char *) tz_rules
[1].name
;
139 compute_offset (unsigned int ss
, unsigned int mm
, unsigned int hh
)
147 return ss
+ mm
* 60 + hh
* 60 * 60;
150 /* Parses the time zone name at *TZP, and writes a pointer to an
151 interned string to tz_rules[WHICHRULE].name. On success, advances
152 *TZP, and returns true. Returns false otherwise. */
154 parse_tzname (const char **tzp
, int whichrule
)
156 const char *start
= *tzp
;
157 const char *p
= start
;
158 while (('a' <= *p
&& *p
<= 'z')
159 || ('A' <= *p
&& *p
<= 'Z'))
161 size_t len
= p
- start
;
165 if (__glibc_unlikely (*p
++ != '<'))
168 while (('a' <= *p
&& *p
<= 'z')
169 || ('A' <= *p
&& *p
<= 'Z')
170 || ('0' <= *p
&& *p
<= '9')
171 || *p
== '+' || *p
== '-')
174 if (*p
++ != '>' || len
< 3)
178 const char *name
= __tzstring_len (start
, len
);
181 tz_rules
[whichrule
].name
= name
;
187 /* Parses the time zone offset at *TZP, and writes it to
188 tz_rules[WHICHRULE].offset. Returns true if the parse was
191 parse_offset (const char **tzp
, int whichrule
)
193 const char *tz
= *tzp
;
195 && (*tz
== '\0' || (*tz
!= '+' && *tz
!= '-' && !isdigit (*tz
))))
199 if (*tz
== '-' || *tz
== '+')
200 sign
= *tz
++ == '-' ? 1L : -1L;
205 unsigned short int hh
;
206 unsigned short mm
= 0;
207 unsigned short ss
= 0;
209 if (sscanf (tz
, "%hu%n:%hu%n:%hu%n",
210 &hh
, &consumed
, &mm
, &consumed
, &ss
, &consumed
) > 0)
211 tz_rules
[whichrule
].offset
= sign
* compute_offset (ss
, mm
, hh
);
213 /* Nothing could be parsed. */
216 /* Standard time defaults to offset zero. */
217 tz_rules
[0].offset
= 0;
221 /* DST defaults to one hour later than standard time. */
222 tz_rules
[1].offset
= tz_rules
[0].offset
+ (60 * 60);
223 *tzp
= tz
+ consumed
;
227 /* Parses the standard <-> DST rules at *TZP. Updates
228 tz_rule[WHICHRULE]. On success, advances *TZP and returns true.
229 Otherwise, returns false. */
231 parse_rule (const char **tzp
, int whichrule
)
233 const char *tz
= *tzp
;
234 tz_rule
*tzr
= &tz_rules
[whichrule
];
236 /* Ignore comma to support string following the incorrect
237 specification in early POSIX.1 printings. */
240 /* Get the date of the change. */
241 if (*tz
== 'J' || isdigit (*tz
))
244 tzr
->type
= *tz
== 'J' ? J1
: J0
;
245 if (tzr
->type
== J1
&& !isdigit (*++tz
))
247 unsigned long int d
= strtoul (tz
, &end
, 10);
248 if (end
== tz
|| d
> 365)
250 if (tzr
->type
== J1
&& d
== 0)
259 if (sscanf (tz
, "M%hu.%hu.%hu%n",
260 &tzr
->m
, &tzr
->n
, &tzr
->d
, &consumed
) != 3
261 || tzr
->m
< 1 || tzr
->m
> 12
262 || tzr
->n
< 1 || tzr
->n
> 5 || tzr
->d
> 6)
266 else if (*tz
== '\0')
268 /* Daylight time rules in the U.S. are defined in the U.S. Code,
269 Title 15, Chapter 6, Subchapter IX - Standard Time. These
270 dates were established by Congress in the Energy Policy Act
271 of 2005 [Pub. L. no. 109-58, 119 Stat 594 (2005)].
272 Below is the equivalent of "M3.2.0,M11.1.0" [/2 not needed
273 since 2:00AM is the default]. */
275 if (tzr
== &tz_rules
[0])
291 if (*tz
!= '\0' && *tz
!= '/' && *tz
!= ',')
295 /* Get the time of day of the change. */
300 negative
= *tz
== '-';
302 /* Default to 2:00 AM. */
303 unsigned short hh
= 2;
304 unsigned short mm
= 0;
305 unsigned short ss
= 0;
307 sscanf (tz
, "%hu%n:%hu%n:%hu%n",
308 &hh
, &consumed
, &mm
, &consumed
, &ss
, &consumed
);;
310 tzr
->secs
= (negative
? -1 : 1) * ((hh
* 60 * 60) + (mm
* 60) + ss
);
313 /* Default to 2:00 AM. */
314 tzr
->secs
= 2 * 60 * 60;
316 tzr
->computed_for
= -1;
321 /* Parse the POSIX TZ-style string. */
323 __tzset_parse_tz (const char *tz
)
325 /* Clear out old state and reset to unnamed UTC. */
326 memset (tz_rules
, '\0', sizeof tz_rules
);
327 tz_rules
[0].name
= tz_rules
[1].name
= "";
329 /* Get the standard timezone name. */
330 if (parse_tzname (&tz
, 0) && parse_offset (&tz
, 0))
332 /* Get the DST timezone name (if any). */
335 if (parse_tzname (&tz
, 1))
337 parse_offset (&tz
, 1);
338 if (*tz
== '\0' || (tz
[0] == ',' && tz
[1] == '\0'))
340 /* There is no rule. See if there is a default rule
342 __tzfile_default (tz_rules
[0].name
, tz_rules
[1].name
,
343 tz_rules
[0].offset
, tz_rules
[1].offset
);
352 /* Figure out the standard <-> DST rules. */
353 if (parse_rule (&tz
, 0))
358 /* There is no DST. */
359 tz_rules
[1].name
= tz_rules
[0].name
;
360 tz_rules
[1].offset
= tz_rules
[0].offset
;
367 /* Interpret the TZ envariable. */
369 tzset_internal (int always
)
371 static int is_initialized
;
374 if (is_initialized
&& !always
)
378 /* Examine the TZ environment variable. */
380 if (tz
&& *tz
== '\0')
381 /* User specified the empty string; use UTC explicitly. */
384 /* A leading colon means "implementation defined syntax".
385 We ignore the colon and always use the same algorithm:
386 try a data file, and if none exists parse the 1003.1 syntax. */
387 if (tz
&& *tz
== ':')
390 /* Check whether the value changed since the last run. */
391 if (old_tz
!= NULL
&& tz
!= NULL
&& strcmp (tz
, old_tz
) == 0)
392 /* No change, simply return. */
396 /* No user specification; use the site-wide default. */
399 tz_rules
[0].name
= NULL
;
400 tz_rules
[1].name
= NULL
;
402 /* Save the value of `tz'. */
404 old_tz
= tz
? __strdup (tz
) : NULL
;
406 /* Try to read a data file. */
407 __tzfile_read (tz
, 0, NULL
);
411 /* No data file found. Default to UTC if nothing specified. */
413 if (tz
== NULL
|| *tz
== '\0'
414 || (TZDEFAULT
!= NULL
&& strcmp (tz
, TZDEFAULT
) == 0))
416 memset (tz_rules
, '\0', sizeof tz_rules
);
417 tz_rules
[0].name
= tz_rules
[1].name
= "UTC";
419 tz_rules
[0].type
= tz_rules
[1].type
= J0
;
420 tz_rules
[0].change
= tz_rules
[1].change
= (time_t) -1;
425 __tzset_parse_tz (tz
);
428 /* Figure out the exact time (as a time_t) in YEAR
429 when the change described by RULE will occur and
430 put it in RULE->change, saving YEAR in RULE->computed_for. */
433 compute_change (tz_rule
*rule
, int year
)
437 if (year
!= -1 && rule
->computed_for
== year
)
438 /* Operations on times in 2 BC will be slower. Oh well. */
441 /* First set T to January 1st, 0:00:00 GMT in YEAR. */
443 t
= ((year
- 1970) * 365
444 + /* Compute the number of leapdays between 1970 and YEAR
445 (exclusive). There is a leapday every 4th year ... */
446 + ((year
- 1) / 4 - 1970 / 4)
447 /* ... except every 100th year ... */
448 - ((year
- 1) / 100 - 1970 / 100)
449 /* ... but still every 400th year. */
450 + ((year
- 1) / 400 - 1970 / 400)) * SECSPERDAY
;
457 /* Jn - Julian day, 1 == January 1, 60 == March 1 even in leap years.
458 In non-leap years, or if the day number is 59 or less, just
459 add SECSPERDAY times the day number-1 to the time of
460 January 1, midnight, to get the day. */
461 t
+= (rule
->d
- 1) * SECSPERDAY
;
462 if (rule
->d
>= 60 && __isleap (year
))
468 Just add SECSPERDAY times the day number to the time of Jan 1st. */
469 t
+= rule
->d
* SECSPERDAY
;
473 /* Mm.n.d - Nth "Dth day" of month M. */
476 int d
, m1
, yy0
, yy1
, yy2
, dow
;
477 const unsigned short int *myday
=
478 &__mon_yday
[__isleap (year
)][rule
->m
];
480 /* First add SECSPERDAY for each day in months before M. */
481 t
+= myday
[-1] * SECSPERDAY
;
483 /* Use Zeller's Congruence to get day-of-week of first day of month. */
484 m1
= (rule
->m
+ 9) % 12 + 1;
485 yy0
= (rule
->m
<= 2) ? (year
- 1) : year
;
488 dow
= ((26 * m1
- 2) / 10 + 1 + yy2
+ yy2
/ 4 + yy1
/ 4 - 2 * yy1
) % 7;
492 /* DOW is the day-of-week of the first day of the month. Get the
493 day-of-month (zero-origin) of the first DOW day of the month. */
497 for (i
= 1; i
< rule
->n
; ++i
)
499 if (d
+ 7 >= (int) myday
[0] - myday
[-1])
504 /* D is the day-of-month (zero-origin) of the day we want. */
510 /* T is now the Epoch-relative time of 0:00:00 GMT on the day we want.
511 Just add the time of day and local offset from GMT, and we're done. */
513 rule
->change
= t
- rule
->offset
+ rule
->secs
;
514 rule
->computed_for
= year
;
518 /* Figure out the correct timezone for TM and set `__tzname',
519 `__timezone', and `__daylight' accordingly. */
522 __tz_compute (time_t timer
, struct tm
*tm
, int use_localtime
)
524 compute_change (&tz_rules
[0], 1900 + tm
->tm_year
);
525 compute_change (&tz_rules
[1], 1900 + tm
->tm_year
);
531 /* We have to distinguish between northern and southern
532 hemisphere. For the latter the daylight saving time
533 ends in the next year. */
534 if (__builtin_expect (tz_rules
[0].change
535 > tz_rules
[1].change
, 0))
536 isdst
= (timer
< tz_rules
[1].change
537 || timer
>= tz_rules
[0].change
);
539 isdst
= (timer
>= tz_rules
[0].change
540 && timer
< tz_rules
[1].change
);
541 tm
->tm_isdst
= isdst
;
542 tm
->tm_zone
= __tzname
[isdst
];
543 tm
->tm_gmtoff
= tz_rules
[isdst
].offset
;
547 /* Reinterpret the TZ environment variable and set `tzname'. */
553 __libc_lock_lock (tzset_lock
);
560 __tzname
[0] = (char *) tz_rules
[0].name
;
561 __tzname
[1] = (char *) tz_rules
[1].name
;
564 __libc_lock_unlock (tzset_lock
);
566 weak_alias (__tzset
, tzset
)
568 /* Return the `struct tm' representation of *TIMER in the local timezone.
569 Use local time if USE_LOCALTIME is nonzero, UTC otherwise. */
571 __tz_convert (const time_t *timer
, int use_localtime
, struct tm
*tp
)
573 long int leap_correction
;
578 __set_errno (EINVAL
);
582 __libc_lock_lock (tzset_lock
);
584 /* Update internal database according to current TZ setting.
585 POSIX.1 8.3.7.2 says that localtime_r is not required to set tzname.
586 This is a good idea since this allows at least a bit more parallelism. */
587 tzset_internal (tp
== &_tmbuf
&& use_localtime
);
590 __tzfile_compute (*timer
, use_localtime
, &leap_correction
,
591 &leap_extra_secs
, tp
);
594 if (! __offtime (timer
, 0, tp
))
597 __tz_compute (*timer
, tp
, use_localtime
);
598 leap_correction
= 0L;
602 __libc_lock_unlock (tzset_lock
);
613 if (__offtime (timer
, tp
->tm_gmtoff
- leap_correction
, tp
))
614 tp
->tm_sec
+= leap_extra_secs
;
623 libc_freeres_fn (free_mem
)
625 while (tzstring_list
!= NULL
)
627 struct tzstring_l
*old
= tzstring_list
;
629 tzstring_list
= tzstring_list
->next
;